In addition to conventional grinding stones, grinding devices for knives and other cutting tools can be separated into two main groups, one of which refers to devices having stationary grinding means requiring that the edge is manually moved forth and back for grinding, and the other main group comprising motor driven grinding means which are driven to move relative to the edge.
The later group is dominated by devices wherein upon grinding the edge has an essentially tangential orientation with respect to a rotating grinding means. As an example on the latter type of devices, reference can be made to the German publication DE-A1-100 44 614. A characteristic feature in these grinding devices is that the polishing direction essentially follows the length direction of the edge, which is not always optimal.